Positioning of elements in a box with Flexbox - css

Question

I have been trying to make a row of responsive boxes present a nicer look. After lots of effort and googling, I am here to get a word from experts. Please check the image below:
Outermost red is a bootstrap flexible row with display:flex;
Each box, the first of which is represented by green box, has flex: 1 ...;
Until this point, there is no issue and my CSS works perfect on all screen sizes showing all the boxes in same height and width. I just have two issues which I need help on.
Issue 1:
I need that lower part of box (represented by orange border) may always get positioned to the bottom of green box. This way all the buttons will appear in same line.
I tried to use a wrapper div in each box and then set position attribute for wrapper to relative and those of inner divs (yellow & orange) to absolute. Then I set the lower one to bottom: 0px;. But it does not work with flex and needs me to mention fixed height of wrapper which I cannot mention.
Issue 2:
In the box with the blue border I need the text of all lines to be justified except the last line which should be left aligned.

Answer 1

Issue 1
Assign display: flex to the div that is presented by the green box. After that, add align-self: flex-end; to the orange box. The orange box should now be displayed at the end of the green box.
Issue 2
Use the following fix to achieve what you want:
.blue-box {
text-align: justify;
-moz-text-align-last: right;
text-align-last: left;
}
The problem is that this wis not supported by Safari on Mac and iOS devices. You would have to add more markup to also cover Safari. An example would be to wrap each text line into a p tag if it's possible. Then you could do this:
.blue-box p {
text-align: justify;
}
.blue-box p:last-child {
text-align: left;
}
Please report back if the fixes do work for you or not.

Answer 2

The best way to solve this is to use flexbox.
.promo-boxes {
width: 100%;
display: flex;
justify-content: space-between;
background-color:black;
}
.promo-box {
width: 100px;
border: solid 1px #ccc;
background-color:red;
display: flex;
}
.btns-wrapper {
margin-top: auto;
align-self: flex-end;
}
<div class="promo-boxes">
<div class="promo-box">
<div>test 2</div>
<div class="btns-wrapper">
<button>
subscribe
</button>
</div>
</div>
<div class="promo-box">
<div>
test 3
</div>
<div class="btns-wrapper">
</div>
</div>
<div class="promo-box">
<div>
test 4 <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
loooong
</div>
<div class="btns-wrapper">
</div>
</div>
</div>